The present invention relates generally to an antenna diversity system, and in particular to selecting one of a plurality of antennas and one of a plurality of alternative receiving frequencies to determine a desirable antenna and frequency combination.
An antenna and frequency diversity receiving apparatus typically includes a receiver connected to one of several spatially separated antennas and tunable to one of several alternative receiving frequencies. Such an apparatus is oftentimes used with a mobile receiver, for example, a radio receiver in a motor vehicle. As such, a plurality of antennas are integrated within the windows of the motor vehicle. A selection circuit selects according to prescribable criteria one of the antennas to be connected to the receiver (e.g., the antenna receiving a signal with the greatest field strength). Signals to be received may emanate from various types of transmitters, for example, a radio broadcasting apparatus, a television broadcasting apparatus or telephone equipment. An evaluation circuit selects one of the alternative receiving frequencies to which the receiver will be tuned. In order to achieve the best possible signal reception, it is necessary to determine the best antenna and frequency combination.
What is needed is a technique for determining the best antenna and frequency combination as quickly and reliably as possible from both the plurality of available antennas and the plurality of available receiving alternative frequencies.